Fix: Dev scorer wasn't working with SourceOnly and TargetOnly

[YanisLalou]

Issue:

The SourceOnly and TargetOnly methods were not functioning as expected.

Cause:

The default behavior was overriding the layer names, setting them to None, which caused the issue.

Solution:

• Removed the default None assignment for layer names in the selectSource and selectTarget methods.

Next Steps:

• Add relevant test cases to ensure proper functionality.